Python is running fast(er).
Yeah, I know, if you wanted speed, you wouldn't be using python, but still...
Personally, I prefer lua, but python's huge standard library beats lua's better design every day of the week. It's also nice not to have to explicitly "end" every code block. But lua's tables are so much better than anything python (or gdscript) offers. Code becomes much simpler when you just get null back from accessing a non-existing key. (And, yes, I know how to use .get() -- it's not as good.)